app/ --> all of the files to be used in production
css/ --> css files
app.css --> default stylesheet
img/ --> image files
index.html --> app layout file (the main html template file of the app)
index-async.html --> just like index.html, but loads js files asynchronously
js/ --> javascript files
app.js --> application
controllers.js --> application controllers
directives.js --> application directives
filters.js --> custom angular filters
services.js --> custom angular services
lib/ --> angular and 3rd party javascript libraries
angular/
angular.js --> the latest angular js
angular.min.js --> the latest minified angular js
angular-*.js --> angular add-on modules
version.txt --> version number
partials/ --> angular view partials (partial html templates)
partial1.html
partial2.html
config/karma.conf.js --> config file for running unit tests with Karma
config/protractor-conf.js --> config file for running e2e tests with Protractor
scripts/ --> handy shell/js/ruby scripts
e2e-test.sh --> runs end-to-end tests with Karma (*nix)
e2e-test.bat --> runs end-to-end tests with Karma (windows)
test.bat --> autotests unit tests with Karma (windows)
test.sh --> autotests unit tests with Karma (*nix)
web-server.js --> simple development webserver based on node.js
test/ --> test source files and libraries
e2e/ -->
scenarios.js --> end-to-end specs
lib/
angular/ --> angular testing libraries
angular-mocks.js --> mocks that replace certain angular services in tests
angular-scenario.js --> angular's scenario (end-to-end) test runner library
version.txt --> version file
unit/ --> unit level specs/tests
controllersSpec.js --> specs for controllers
directivessSpec.js --> specs for directives
filtersSpec.js --> specs for filters
servicesSpec.js --> specs for services